Alleima® 13RM19 Strip steel

Datasheet updated

2022-09-01 14:11
(supersedes all previous editions)

Alleima® 13RM19 is a stainless spring steel combining high mechanical strength with a non-magnetic structure. This combination of properties has previously been found mainly in expensive Co-Ni-base or Cu-Be alloys. Corrosion resistance is comparable to ASTM 301.

Alleima® 13RM19 also possesses good fatigue properties and excellent ductility, which makes it a most suitable choice for springs and other high-strength applications where ferromagnetic materials cannot be used.

Alleima® 13RM19 main characteristics:

  • Non-magnetic structure in all conditions
  • High mechanical strength in the cold rolled condition. Strength can be further increased by tempering, without any effect on the non-magnetic structure.
  • High elastic limit and energy storing capacity in the cold rolled and tempered condition which is important for spring applications.

Service temperature: up to 250°C (480°F)

Standards

  • EN Number: 1.4369
  • EN Name: X 11 CrNiMnN 19-8-6

Chemical composition (nominal)

Chemical composition (nominal) %
C Si Mn P S Cr Ni
0.11 0.8 6.0 ≤0.030 ≤0.015 18.5 7

Others: N=0.25

Applications

The combination of high strength and non-magnetic behavior makes Alleima® 13RM19 very suitable for springs and other high strength components in the electronic and computer industries.

Typical products where Alleima® 13RM19 can be used to advantage are printers, springs in generators, magnetic instrument housings, components in measuring instruments, zipper parts and other components that require non-magnetic properties. The grade is also used in surgical tools and other equipment for open architecture magnets in which surgery is performed simultaneously with magnetic resonance imaging.

The high strength also makes Alleima® 13RM19 suitable as a cable armoring material for high voltage cables, where transmission losses must be kept low.

Corrosion resistance

Alleima® 13RM19 has a corrosion resistance comparable to that of ASTM 301/304. The high nitrogen content is known to be beneficial for resistance to pitting and crevice corrosion. However, all austenitic steels of this type are susceptible to stress corrosion cracking (SCC) when in contact with chloride solutions at elevated temperatures.

Bending

The values given below have been obtained by bending according to Swedish standard SS 11 26 26 method 3 (in a 90° V-block with a 25 mm die opening, a sample of 35 mm width, turned so that the burrs of the blanked edges face into the bend). They can be used as guidance for the smallest recommended bending radius.

Nominal tensile strength, Rm Thickness (t) Min. bending radius*)
MPa mm //
1300 0.25 0.5 t t
1300 0.50 0.5 t 4 t
1500 0.25 1.5 t 3.5 t
1500 0.50 1.5 t 6 t

⊥ Bend transverse to the rolling direction
// Bend parallel to the rolling direction

Forms of supply

Strip steel can be supplied in coils, bundles, on plastic spools or in lengths. The edges can be either slit, deburred or smoothly rounded.

Conditions and dimensions

Alleima® 13RM19 is supplied in the cold rolled or solution annealed (bright annealed or annealed
and pickled) condition.

Condition Tensile strength, Rm Thickness
MPa ksi mm in.
Annealed 850 123 0.03-4 0.0012-0.16
Cold rolled 1100 160 0.025-3.2 0.001-0.13
Cold rolled 1300 189 0.02-2.8 0.0008-0.11
Cold rolled 1500 218 0.015-1.9 0.0006-0.075
Cold rolled 1600 232 0.015-0.9 0.0006-0.035

Widths: 2-345 mm (0.08 - 13.6 in.)

Tolerances

The thickness and width tolerances are +/- tolerances to the nominal size. The normal tolerance classes for most of our strip products are T2 and B1. Tighter tolerances as well as other tolerance limits can be offered upon request.

Heat treatment

The strength of cold rolled steel can be increased by a tempering operation at 480°C (896°F) for 2 hours. For cold rolled Alleima® 13RM19 with a tensile strength above about 1400 MPa, an increase in tensile strength of about 100-200 MPa (14.5-29 ksi) can be expected. Further information on the nominal tempering effect can be seen under the 'Mechanical properties' section. This heat treatment is also beneficial for relaxation and fatigue resistance.

Tempering is normally carried out by the customer after forming. To avoid discoloration, parts should be carefully cleaned before heat treatment.

Tempering in open air furnaces gives a harmless brownish oxide on the surface.

Mechanical properties

Static strength

Nominal values at 20°C (68°F)
Condition1)Tensile strength, RmProof strength,
Rp0,2a)
Elongation, A11,3
MPaksiMPaksi%
A 850 123 470 68 45
C 1100 160 975 142 12
CT 1130 164 1020 148 11
C 1300 189 1150 167 10
CT 1350 196 1220 177 8
C 1500 218 1350 196 3
CT 1650 239 1500 218 2
C 1600 232 1440 209 2
CT 1800 261 1630 237 1

1) A = Annealed, C = Cold rolled, CT = Cold rolled and tempered, 480°C (896°F)/2 h.
See further under section 'Heat treatment'.

a) Rp0.2corresponds to 0.2% offset yield strength.
1 MPa = 1 N/mm2

Fatigue strength

Nominal values at 20°C (68°F) in a normal dry atmosphere. The fatigue limit is defined as the stress at which 50% of the specimens withstand a minimum of 2 million load cycles.

Reversed bending stress

Average stress = 0
Bending transversal to rolling direction.

Comparison made for different thicknesses and tensile strength levels.

Tensile strength, RmThicknessFatigue limit
MPaksimmin.MPaksi
1600 232 0.40 0.016 ± 605 ±88
1800 261 0.20 0.008 ± 680 ±99
1800 261 0.40 0.016 ± 635 ±92

Fluctuating tensile stress

Minimum stress = 0
Specimens parallel to rolling direction.

Comparison made for different thicknesses and tensile strength levels.

Tensile strength, RmThicknessFatigue limit
MPaksimmin.MPaksi
1600 232 0.40 0.016 500 ± 500 73 ± 73
1800 261 0.40 0.016 535 ± 535 78 ± 78

Physical properties

The physical properties of a steel relate to a number of factors, including alloying elements, heat treatment and manufacturing route, but the following data can generally be used for rough calculations. These values refer to cold rolled material, at a temperature of 20oC(68oF) unless otherwise stated.

Density: 7.9 g/cm3 (0.29 lb/in.3)

Resistivity: 0.7 μΩm (27.6 μΩin.)

Modulus of elasticity: 190 000 MPa (27600 ksi)

Thermal expansion mean values in temperature ranges (x10-6)
Temperature, °Cper °CTemperature, °Fper °F
30 - 100 16.5 85 - 200 9
30 - 200 17 85 - 400 9.5
30 - 300 18 85 - 550 10
Thermal conductivity
Temperature, °CW/m °CTemperature, °FBtu/ft h °F
20 15 68 8.5
100 16 200 9
300 19 600 11

Magnetic properties

From a magnetic point of view, materials can be divided into three groups, para-, dia- and ferromagnetic materials. In many practical cases, para- and diamagnetic materials will, however, interact strongly with the magnetic fields. In some cases, the ferromagnetic properties are desired, while in other situations no interaction with a magnetic field can be accepted.

The magnetic properties of a material are expressed as the magnetic susceptibility, c, or often as the magnetic permeability m = 1 + c. By definition, the magnetic susceptibility is placed at 0 for vacuums, from which it follows that m0=1. The magnetic permeability for a certain material is expressed as mr , which is its relative permeability versus vacuum. Further, as mr may vary with the magnetic field strength, the maximum value of mr max is often given as a representative value of the material.

Most types of high strength steel are ferromagnetic in spring hard conditions. The spring properties are achieved by hardening, e.g. carbon and chromium steels, or by cold rolling e.g. ASTM 301 (EN 1.4310). The origin of the properties is the martensitic structure. Higher alloyed steels e.g. ASTM 316, besides being more expensive, suffer from difficulties in reaching a high strength by cold working. If high strength is needed, together with a non-magnetic (para-magnetic) material, the option has traditionally been expensive Copper-Beryllium or Cobalt base alloys.

Alleima® 13RM19 is alloyed in such a way that the structure is very stable against a martensitic transformation but still allows a strong work hardening effect at deformation. Therefore, it is possible to obtain mechanical properties similar to ASTM 301, but maintain a non-magnetic structure. The low permeability is not influenced by a tempering operation. Alleima® 13RM19 also remains completely non-magnetic down to extremely low temperatures.

The following diagram shows typical values for the maximum relative magnetic permeability for Alleima® 13RM19, compared to ASTM 301 and 304.

Typical values at 20°C (68°F)
Condition Tensile strength, Rm Maximum µr max
MPa ksi
A 850 123 1.003
C 1300 189 1.005
CT 1350 196 1.005
C 1600 232 1.03
CT 1800 261 1.03

Alleima® 13RM19 remains non-magnetic down to very low temperatures. The diagram below shows the magnetic permeability down to 4.2 K (-268.95°C) for material in the annealed condition.

Welding

Alleima® 13RM19, like most austenitic stainless steels, has good weldability. Welding, however, introduces excess heat into the material closest to the weld that breaks down the structure formed by cold working. As a consequence, this will decrease the mechanical properties of the welded area. The lowest practical heat input, <1,0 kJ/mm, and interpass temperature for multipass welding, <100°C (210oF), is recommended.

In most cases, the TIG (GTAW) method is preferable. It can be used either autogenously (without filler metal) or with filler metal. In both cases, pure argon (99,99%) should be used as the shielding gas. If a low loss of nitrogen is essential, Argon with 1 - 2% Nitrogen can be used instead.

When filler metal is used, the recommendation is to do it according to standard ISO 14343-A: 19 9 L; AWS A5.9/ASME SFA-5.9: ER308L; W.Nr.: 1.4316 and ISO 14343: 19 9 L Si; AWS A5.9/ASME SFA-5.9: ER308LSi; W.Nr.: 1.4316.

Due to the high carbon content of Alleima® 13RM19, there is also a risk of carbide precipitation at the grain boundaries of the material in the heat affected zone (HAZ), which may decrease the corrosion resistance of the material in certain environments

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.